Along with progress of industry, consumption of traditional energy sources such as coal, oil and nature gas continually rises, and since stock of the nature energy sources is limited, a new alternative energy source has to be developed to replace the traditional energy sources, and a fuel cell is an important an practical selection.
In brief, the fuel cell is basically a power generation device capable of converting chemical energy into electrical energy through a reverse reaction of water electrolysis. Regarding a proton exchange membrane fuel cell, it is mainly composed of a membrane electrode assembly (MEA) and two electrode plates.
The MEA has an anode and a cathode, and a fuel (for example, hydrogen) is transmitted through the anode, and an oxidant (for example, air) with humidity is transmitted through the cathode, where an oxidation reaction is taken place at the anode, and a reduction reaction is taken place at the cathode, and a chemical formula thereof is as follows:
Anode: H2→2H++2 e−
Cathode: O2+4H++4 e−→2H2O
When the hydrogen of the anode contacts a catalyst adjacent to the proton exchange membrane, hydrogen molecules are dissociated into hydrogen ions and electrons, where the electrons flow in an electrical circuit, and the hydrogen ions directly pass through the proton exchange membrane from the anode to reach the cathode. Under a function of a cathode catalyst, the electrons reached through the electrical circuit are combined with oxygen to form oxygen ions, and the oxygen ions are combined with the hydrogen ions passing through the proton exchange membrane to form water molecules, which is the oxidation and reduction reaction process of electrochemical, and electricity is provided to a load through the electrical circuit.
However, the cost and lifespan of the fuel cell are major obstacles for commercialization of the fuel cell, and system problems caused by water and heat management and stoichiometry control has to be first resolved.